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Particle engulfment dynamics under oscillating crystal growth conditions

 
: Tao, Y.; Sorgenfrei, T.; Jauß, T.; Cröll, A.; Reimann, C.; Friedrich, J.; Derby, J.J.

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Journal of Crystal Growth 468 (2017), S.24-27
ISSN: 0022-0248
Englisch
Zeitschriftenaufsatz
Fraunhofer IISB ()

Abstract
To better understand the physical mechanisms behind particle engulfment dynamics under fluctuating solidification velocities, transient simulations are performed for a SiC particle in a silicon solidification system with oscillating growth rates using a rigorous finite-element model developed previously. Simulations reveal complicated behaviors that require a re-examination of the classical notion of a steady-state, critical growth velocity, v c, for particle engulfment. Under sinusoidal growth variations at a frequency representative of turbulent fluctuations in a large-scale melt, stable pushing states featuring nonlinear particle-growth front oscillations can arise, even when the maximum growth velocity slightly exceeds v c. However, higher-amplitude growth oscillations at the same frequency are shown to result in particle engulfment. Significantly, engulfment under such dynamic conditions can occur at average solidification rates far below the steady-state critical velocity, a behavior consistent with many experimental observations.

: http://publica.fraunhofer.de/dokumente/N-445158.html